Project Summary All eukaryotic cells rapidly build cytoskeleton-based structures to heal themselves and to power cell division. These structures, after they have accomplished their allotted tasks, are then disassembled. How is it that these transient cytoskeletal arrays are brought into being where and when they are needed? Our work is directed at providing answers to both of these questions. It will involve a combination of approaches, including high resolution imaging of transient cytoskeletal arrays in living cells, biochemical characterization of some of the parts of these arrays, and manipulation of those parts in living cells. Successful completion of this work will provide new insights into diseases such as the muscular dystrophies and cancer, which can occur when transient cytoskeletal arrays either fail to assemble or assemble improperly.